1) Field of the Invention
The present invention relates to insulated formwork panels and to a process for their manufacture.
More particularly, the invention relates to prefabricated formwork panels that are made of an insulating material and are reinforced with a strong metal core. Such panels can be used in combination with other identical panels to form a mold into which concrete can be casted. After casting of the concrete, the panels are left in place, thereby providing a concrete wall with insulating panels on both of its sides.
2) Description of the Prior Art
U.S. Pat. No. 4,888,931 in the name of the present inventor discloses an insulating formwork for use to manufacture a concrete wall. This formwork is made of foam panels that are preferably made of expanded polystyrene and are connected to each other in parallel relationship by means of tie-rods engaged into angle-irons fitted into slits provided into the upper and lower edges of each panel. Once assembled, the panels define a concrete formwork into which concrete can be poured.
U.S. Pat. No. 4,604,843 in the name of ETABLISSEMENTS PATURLE discloses a formwork for use to manufacture a concrete wall. This formwork is made of insulating foam panels reinforced by a core consisting essentially of a mesh bonded to an array of parallel tubes. As an alternative to the mesh, reference is also made to other reinforcing material such as a xe2x80x9cperforated or imperforated foilxe2x80x9d or xe2x80x9ca grid of wires, rods of filaments . . . , a synthetic resin fabric or metallic or non-metallic filamentsxe2x80x9d (see column 4, lines 36 to 49). The panels are connected to each other in parallel relationship by means of horizontal elements having a ladder like configuration. This patent also discloses that the panels are preferably made of  less than  less than  a high density synthetic resin such as expanded polystyrene, extruded polystyrene foam, polyurethane foam or a foamed phenolformaldehyde or like resin.
U.S. Pat. No. 4,516,372 in the name of George A. GRUTSCHE discloses a concrete formwork made of modules comprising two parallel spaced apart panels preferably made of insulating foam. Each module also comprises small backing plates extending on the external surfaces of the eternal upper and lower edges of the panels. These plates are connected to each other by means of tie-rods extending through the panels. This patent discloses that the panels are preferably made of a low density plastic foam such as polyurethane that can be injected or poured into forms. This patent does not disclose or suggest that reinforcing cores or grids be incorporated into the panels.
Except for U.S. Pat. No. 4,516,372 which discloses that the panels are preferably manufactured by injection or pouring of the foam into molds at the job site, none of these patents discloses how the panels are manufactured. A fortiori, none of these three patents discloses or suggests how panels incorporating a reinforcing metal core may actually be manufactured industrially in a continuous manner.
A first object of the present invention is to provide an insulated formwork panel that incorporates a corrugated reinforcing metal core and can easily and efficiently be manufactured in a continuous manner. Thanks to its reinforcing metal core that is corrugated, the panel is very strong and resistant to pressure whatever be the direction in which such pressure is exerted. Of course, since it is made of foam, the panel is also heat and/or cold insulating and moisture resistant. Therefore, it can efficiently be used to build up permanent self-supporting formworks into which concrete can be cast to form insulated walls.
In accordance with the invention, this first object is achieved with an insulated formwork panel having a main body made of insulating foam. This main body has a given length, a given height with opposite edges and a given thickness and incorporates a corrugated reinforcing metal core embedded into the foam. The corrugated metal core is of substantially the same height as the main body and extending within the same over all the length thereof.
Preferably, the metal core consists of a grid comprising a first set of spaced apart straight rods extending along the height of the main body and a second set of spaced-apart rods extending along the length of the main body. The rods of the second set are connected to the rods of the first set and are corrugated to form V-shaped zigzags of such a depth that the core is of an average thickness close to the thickness of the main body in order to fill up the same.
More preferably, the formwork panel further comprises a T-shaped bar positioned onto one of the opposite edges of the main body to facilitate connection of tie-rods. The bar has a top portion with two opposite sides and a leg portion. One side of the top portion and the leg portion extend flat onto one side of the main body and onto one of its opposite edges, respectively, over all the length of the main body.
Thanks to the very specific structure and size of its metal core, the panel according to the invention is very strong and resistant, thereby making it useful to build up permanent, self-supporting formworks.
Another object of the present invention is to provide a process for the industrial manufacture of insulated formwork panels of the above described type.
The process according to the invention comprises the basic steps of:
manufacturing the metal cores of the formwork panels in the form of a continuous metal core band;
supplying the metal core band onto a main conveyor having an inlet in which the metal core band is continuously fed, and an outlet;
preparing a mixture of components that react with each other to make the insulating foam;
continuously injecting the mixture at the inlet of the main conveyor;
compressing the foam that is being formed and expands along the main conveyor so as to form a continuous main body band having a given height and given thickness, the continuous main body band incorporating the continuous metal core band; and
cutting at a given length the continuous main body band and the continuous metal core band incorporated therein at the outlet of the main conveyor to obtain the requested panels.
Preferably, the compressing step is carried out by a secondary conveyor extending on top of the main conveyor. In such a case, the process comprises the additional steps of:
positioning a bottom layer of supporting material onto the main conveyor upstream of the inlet thereof so that the metal core band and the mixture of compounds be respectively supplied and injected on top of the bottom layer, the bottom layer being continuous and having side edges;
positioning a top layer of supporting material onto the secondary conveyor so as to cover the metal core band and foam that is being formed, the top layer being continuous and having side edges; and
folding and positioning the side edges of the bottom and top layers so as to control expansion of the foam and height and thickness adjustment of the continuous main body band.
More preferably, the process may also comprise the additional steps of:
supplying a continuous T-shaped bar into the inlet of the main conveyor, said bar having a top portion with two opposite sides and a leg portion and being supplied in such a manner that one side of its top portion and its leg portion extend flat onto one side and one of the opposite edges of the continuous main body band and, respectively, and
cutting the continuous T-shaped bar together with the continuous main body band and the continuous metal core band incorporated therein at the outlet of the main conveyor.
The present invention and its numerous advantages will be better understood upon reading the following, non-restrictive description of a preferred embodiment thereof, made with reference to the appended drawings.